Nucleating composition and thermoplastic polymer composition comprising such nucleating composition

ABSTRACT

The invention relates to a nucleating composition comprising: (a) a first nucleating agent, which comprises a cyclic dicarboxylate salt compound; and (b) a second nucleating agent, which comprises talc, wherein the cyclic dicarboxylate salt compound has the formula (I):

The invention relates to a nucleating composition comprising a salt of ametal or organic cation of a cyclic dicarboxylic acid as a firstnucleating agent. The invention also relates to a thermoplastic polymercomposition comprising said nucleating composition. The inventionfurther relates to a shaped article comprising said thermoplasticpolymer composition.

Such a nucleating composition is known from document EP 1379368 B1. Thisdocument discloses at least one metal salt of hexahydrophthalic acid(HHPA), e.g. calcium, strontium, lithium and monobasic aluminium salt,to be used as nucleating agent to produce thermoplastic compositionsshowing improved crystallization behaviour.

Several other documents also disclose metal salts employed as nucleatingadditives for thermoplastics. For example, US 2004/0220311 A1 disclosesthe use of a specific hexahydrophthalic acid metal salt, e.g. calcium,strontium, lithium, or monobasic aluminium, as nucleating agent invarious thermoplastics, particularly in polypropylene compositions. WO2006/071721 discloses a thermoplastic composition comprising apolyolefin; a nucleating agent comprising a dicarboxylate salt compound,e.g. bicyclic[2.2.1]heptane dicarboxylate salt, available from Milliken& Company under the trade name Hyperform® HPN-68; a first fatty acidsalt having a first cationic counter ion selected from the groupconsisting of calcium, sodium, lithium and barium, e.g. calciumstearate; and a second fatty acid salt having a second cationic counterion selected from the group of magnesium, aluminium and zinc, e.g. zincstearate.

Nucleating agents are chemical compounds or compositions that enablefaster nucleation or a higher crystallization temperature ofthermoplastic polymers, resulting in productivity gains during theirprocessing and in improved mechanical and physical properties ofarticles made from such thermoplastics. These compounds providenucleation sites for crystal growth during cooling of a thermoplasticmolten composition. In polypropylenes, for example, a higher degree ofcrystallinity and more uniform crystalline structure is obtained byadding a nucleating agent such as talc and carboxylate salts, e.g.sodium benzoate. An overview of nucleating agents used inpolypropylene-based compositions is given for example in Polym. Adv.Technol. 2007, 18, 685-695. However, it is commonly recognized that theuse of nucleating agents is a highly unpredictable technology area.Small changes in a molecular structure of the nucleator can drasticallyalter the ability of a nucleating agent to nucleate effectively apolymer composition. There are still many unknowns regarding the effectof a nucleating agent on polymer morphology during (re-)crystallizationof thermoplastics.

A nucleating composition is known from document EP 1379368 B1. Thisdocument discloses at least one metal salt of hexahydrophthalic acid(HHPA), e.g. calcium, strontium, lithium and monobasic aluminium salt,to be used as nucleating agent to produce thermoplastic compositionsshowing improved crystallization behavior.

Several other documents also disclose metal salts employed as nucleatingadditives for thermoplastics. For example, US 2004/0220311 A1 disclosesthe use of a specific hexahydrophthalic acid metal salt, e.g. calcium,strontium, lithium, or monobasic aluminium, as nucleating agent invarious thermoplastics, particularly in polypropylene compositions. WO2006/071721 discloses a thermoplastic composition comprising apolyolefin; a nucleating agent comprising a dicarboxylate salt compound,e.g. bicyclic[2.2.1]heptane dicarboxylate salt, available from Milliken& Company under the trade name Hyperform® HPN-68; a first fatty acidsalt having a first cationic counter ion selected from the groupconsisting of calcium, sodium, lithium and barium, e.g. calciumstearate; and a second fatty acid salt having a second cationic counterion selected from the group of magnesium, aluminium and zinc, e.g. zincstearate.

There is a demand for improving the mechanical properties of athermoplastic composition such as the flexural modulus and the impactstrength.

It is an object of the invention to provide a nucleating agentcomposition which results in highly improved mechanical properties of athermoplastic composition such as the flexural modulus and the impactstrength.

The objective is achieved according to the invention with a nucleatingcomposition comprising:

(a) a first nucleating agent which comprises a cyclic dicarboxylate saltcompound; and(b) a second nucleating agent which comprises talc,wherein the cyclic dicarboxylate salt compound has the formula (I):

Surprisingly, the nucleating composition of present invention results inhighly improved mechanical properties such as stiffness and impact.

Document US 2007/0213439 A1 also discloses a nucleating compositioncomprising a mixture of two nucleating agents, the first nucleatingagent comprising a dicarboxylate calcium salt, known as Hyperform®HPN-20E, but in this document the second nucleating agent comprises abicyclic[2.2.1]heptane dicarboxylate salt, particularly Hyperform®HPN-68L. Also US 2008/0171834 A1 discloses a dicarboxylate calcium saltas first nucleating agent, but uses a bis-phenol phosphate compound assecond nucleating agent in the nucleating composition. Thus, thesereferences do not disclose nor suggest applying talc as nucleating agentin combination with a dicarboxylate calcium salt.

Additional advantages of the nucleating composition according to thepresent invention include decreased warpage of shaped articles made froma nucleated thermoplastic polymer composition; higher heat deflectiontemperature (HDT) and improved top load.

Additional advantages of the nucleating composition according to thepresent invention include a lower shrinkage caused by temperature changeof shaped articles made from a nucleated thermoplastic polymercomposition, as determined by Coefficient of Linear Thermal Expansion(CLTE) measured according to ASTM D696. The CLTE measures the change inlength per unit length of a material per unit change in temperature.Expressed as in/in/° F. or cm/cm/° C., the CLTE is used to calculate thedimensional change resulting from thermal expansion. CLTE is especiallyimportant when components of an assembly have widely varying thermalexpansion coefficients. Thermal expansion of a material is anotherimportant design factor, particularly in applications where plasticparts composed of polymer components are mated with metal parts or partshaving metal inserts. Shrinkage can also be determined according to ISO294-4 (shrinkage 3-D).

The advantages of the nucleating composition according to the presentinvention include one or combinations of the following favorableproperties: flexural modulus, impact strength, CLTE and shrinkage.

The first nucleating agent in the composition according to the presentinvention comprises a calcium cis-hexahydrophthalate compound of Formula(I).

Hyperform® HPN-20E™ nucleating agent commercialized by Millikencomprises such a calcium cis-hexahydrophthalate compound of Formula (I)and a stearate-containing compound as acid scavenger, e.g. zincstearate.

The nucleating composition according to the present invention comprisestalc as second nucleating agent.

Talc is a common additive in industry, mostly used as reinforcing agentor filler and also as nucleating agent for various polymer compositions.Talc typically is considered a filler when employed in relatively highamounts, for example of about from 10 to 50 wt %, based on the totalpolymer composition. When talc is used under 5 wt %, it is no longerconsidered a filler but acts as nucleating agent.

Talc may be employed in present invention in powder form, preferablyhaving a particle size distribution defined by a d₅₀ of from 0.1 to 20μm; more preferably of from 0.5 to 15 μm; or from 0.7 to 8 μm to improveits nucleating behaviour.

The first nucleating agent and the second nucleating agent can bepresent in the nucleating composition according to the invention inwidely varying amounts, for example in a weight ratio of from 1:1200 to2:1; preferably in a ratio of from 1:500 to 1:1; more preferably in aratio of from 1:100 to 1:2; even more preferably in a ratio of from 1:50to 1:5. The advantage of adding these components within these ratiolimits lies in the possibility to control dimensional stability at fastcycle times and mechanical properties.

The nucleating composition may be employed as powder, dry mix or liquidblend. It may be also mixed with other additives to form an additivepre-blend or it may be blended with a binder material in lowconcentrations, such as a wax or thermoplastic polymer that iscompatible with the polymer for which the composition is intended toserve as nucleating agent. The nucleating composition can also becombined with a thermoplastic polymer as a masterbatch or concentrate.These blends may be provided, optionally, with acid scavengers and otheradditives, such as stabilizers; primary and secondary antioxidants.Suitable acid scavengers can include zinc stearate, calcium stearate orother stearate-based compounds, and hydrotalcite.

The invention also relates to a thermoplastic polymer compositioncomprising a thermoplastic polymer and the nucleating compositionaccording to present invention. As used herein, the term “thermoplastic”refers to a polymeric material that melts upon exposure to sufficientlyhigh temperatures, but re-solidifies (crystallizes) upon cooling.“Thermoplastic” particularly defines polymers having (semi-)crystallinemorphology upon cooling. Suitable examples of thermoplastic polymersinclude polyamides, such as polyamide-6, polyamide-6,6 or polyamide-4,6;polyolefins like polypropylenes, polyethylenes, polybutylene;polyesters, such as polyethylene terephthalate, polybutyleneterephthalate; polyphenylene sulphide; polyurethanes; as well as anytype of polymer blends and compounds and any combinations thereof.Preferably, the thermoplastic polymer is a crystallisable polypropylene,like a propylene homopolymer, a random copolymer, or a so-calledheterophasic or impact copolymer of propylene and ethylene and/oranother alpha-olefin.

In a preferred embodiment of the invention, the thermoplastic polymer isa heterophasic polypropylene copolymer. Such copolymer basically has atleast a two-phase structure, consisting of a propylene-basedsemi-crystalline matrix and a dispersed elastomer phase, typically anethylene-propylene rubber (EPR). These polypropylenes are generallyprepared in one or more reactors, by polymerization of propylene in thepresence of a catalyst system, and subsequent polymerization of apropylene-ethylene mixture; but can also be made by blending different(co)polymers. The resulting polymeric materials are heterophasic;studies have demonstrated the presence of four phases in heterophasicpropylene-based copolymers: crystalline polypropylene, amorphouspolypropylene, crystalline ethylene-propylene rubber, and amorphousethylene-propylene rubber. The advantage of such polymer is improvedimpact resistance, especially at lower temperatures.

Preferably, the thermoplastic polymer is a heterophasic propylenecopolymer comprising a matrix phase comprising propylene and a dispersedphase comprising an ethylene-alpha-olefin elastomer.

Preferably, the heterophasic propylene copolymer comprises from 60 to 92wt % of a matrix phase comprising a propylene homopolymer and/or apropylene copolymer comprising at least 90 wt % of propylene and up to10 wt % of ethylene and/or at least one C₄ to C₁₀ alpha-olefin, and from8 to 40 wt % of dispersed phase comprising an ethylene-alpha-olefinelastomer comprising from 40 to 65 wt % of ethylene and from 35 to 60 wt% of at least one C₃ to C₁₀ alpha-olefin, preferably propylene. Thepercentage of matrix and dispersed component is based on the totalweight of the heterophasic propylene copolymer; comonomer contents arebased on copolymer component.

Preferably, the matrix phase is a propylene homopolymer and the massdispersed phase is an ethylene-alpha-olefin elastomer comprising from 40to 65 wt % of ethylene and from 35 to 60 wt % of propylene.

The thermoplastic polymer composition according to present inventionpreferably contains of from 0.0025 to 0.1 wt % of the first nucleatingagent based on the total thermoplastic polymer composition. A certainminimum amount of the first nucleating agent is needed to effectivelyinfluence nucleating behaviour and properties the polymer compositionfurther comprising talc as nucleating agent; preferably, the nucleatingcomposition contains therefore at least 0.004, 0.005, 0.008, 0.01 wt %of the first nucleating agent. Further increasing the amount of thefirst nucleating agent in the composition to above 0.1 wt % would hardlycontribute to improving the properties of final product. Preferably, thenucleating composition thus contains at most 0.08, 0.06, 0.05, 0.03 wt %of the first nucleating agent. It is a special advantage of the presentinvention that a relatively low amount of the first nucleating agent canbe applied, in combination with the talc-based second nucleating agent;giving not only improved performance but also reducing costs.

The amount of talc used as second nucleating agent in the polymercomposition is preferably of from 0.1 to 5 wt %, more preferably from0.2 to 4 wt %; or from 0.3 to 3 wt %, based on the total thermoplasticpolymer composition. A certain minimum amount of talc is necessary toprovide nucleating effect and good mechanical characteristics, such asstiffness. Preferably, the nucleation composition contains thus at least0.2, 0.3 or even 0.5 wt % of talc. If the nucleating composition wouldcontain more than 3 wt % of talc, the additional amount might onlybehave as filler agent. Preferably, the nucleation composition containstherefore at most 4 or 3 wt % of talc.

Medium to High MFI of Heterophasic Propylene Copolymer

The heterophasic propylene copolymer of the thermoplastic polymercomposition according to the invention preferably has a MFI of at least1 as determined by ISO 1133 at 230° C.; 2.16 kg. In this case, thethermoplastic polymer composition further comprises an organic peroxide.

Organic peroxides are known to be used for viscosity reduction. Thereare different ways in which the organic peroxides behave in conventionaldegradation processes upon heating and melting conditions. On one hand,under certain process conditions, the peroxides initially decompose toproduce free radicals, which then abstract hydrogen from a tertiarycarbon of the polypropylene backbone to form free radicals on thepolymer, and which further recombine. On the other hand, peroxidesinitiate a breakage of the longest chains of the polymer molecules and,subsequently, this results in a decrease in viscosity of the polymer, anincrease in melt flow rate, and a narrower molecular weightdistribution, characteristics which are directly responsible forimproved flow properties of polypropylene in order to make the productmore suitable for certain applications. The extent of each type ofbehaviour is generally influenced by the nature and concentration of theperoxide.

Suitable for present invention are organic peroxides having adecomposition half-life of less than 1 minute at the average processtemperature during formation of the modified polypropylene compositions.Suitable organic peroxides include dialkyl peroxides, e.g. dicumylperoxides, peroxyketals, peroxycarbonates, diacyl peroxides,peroxyesters and peroxydicarbonates. Specific examples of these includebenzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide,di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoato)-3-hexene,1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butylperacetate, α,α′-bis(tert-butylperoxy)diisopropylbenzene (Luperco® 802),2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexene,2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, tert-butyl perbenzoate,tert-butyl perphenylacetate, tert-butyl per-sec-octoate, tert-butylperpivalate, cumyl perpivalate, and any combination thereof.

Preferably, a dialkyl peroxides is employed in the process according tothe present invention. More preferably, the peroxide isα,α′-bis-(tert-butylperoxy)diisopropylbenzene,2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane or3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane.

The organic peroxide of present invention may be applied in amount ofbetween 0.01 wt % and 0.3 wt %, preferably between 0.05 and 0.25 wt %and more preferably between 0.1 and 0.2 wt % based on the totalcomposition.

Medium MFI

The heterophasic propylene copolymer of the thermoplastic polymercomposition according to the invention may have a MFI of at least 1 andless than 10 dg/min.

The composition according to the invention comprising this type ofpropylene copolymer having a medium MFI combines very high impactresistance, also at low temperatures, with high stiffness and offersgood flow properties. By its design it is offering potential of cycletime reduction (shorter holding pressure times, faster injection speedand shorter cooling time), of down gauging and easiness of processingand better esthetics of the parts, reflected in a better sink markcapability. Due to its narrow molecular weight distribution, the verylow tendency to warp and the excellent surface quality, the compositionsaccording to the invention are typically used in injection moulding ofsuitcase shells, crates & boxes, appliances, electronic equipment andautomotive parts including children's car seats. Accordingly, thepresent invention relates to shells, crates, boxes, appliances,electronic equipment and automotive parts including children's car seatscomprising the thermoplastic polymer composition according to theinvention comprising this type of propylene copolymer.

Preferably, the propylene homopolymer of the matrix phase has a MFI ofat least 1 and less than 50 dg/min, e.g. 1 to 10 dg/min.

Preferably, the ethylene-alpha-olefin elastomer of the dispersed phasehas a MFI of 0.01 to 0.5 dg/min.

The mass dispersed phase may be an ethylene-alpha-olefin elastomercomprising from 40 to 60 wt % of ethylene and from 40 to 60 wt % ofpropylene. The polypropylene composition comprising such a heterophasicpropylene copolymer was found to show a very high impact strength aswell as a high flexural modulus.

The mass dispersed phase may be an ethylene-alpha-olefin elastomercomprising from 60 to 65 wt % of ethylene and from 35 to 40 wt % ofpropylene. The polypropylene composition comprising such a heterophaseicpropylene copolymer was found to show an extremely high impact strength.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 1 and lessthan 10 dg/min preferably has a MFI of at least 5 and less than 30dg/min.

The thermoplastic polymer composition according to the invention has ahigh stiffness. For purpose of the present invention, stiffness isdetermined by measuring the flexural modulus according to ASTM D790-10.Flexural modulus was determined on 3.2 mm thick specimens according toISO37/2, parallel (flexural modulus II) and perpendicular (flexuralmodulus L) orientation.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 1 and lessthan 10 dg/min preferably has a flexural modulus L of at least 1000 MPa,preferably at least 1100 MPa, more preferably at least 1200 MPa.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 1 and lessthan 10 dg/min preferably has a flexural modulus II of at least 1000MPa, preferably at least 1100 MPa, more preferably at least 1200 MPa.

The thermoplastic polymer composition according to the invention has ahigh impact strength. For purpose of the present invention, impactstrength is determined by measuring the Izod impact strength at 23° C.according to ISO 180 4A, Test geometry: 65*12.7*3.2 mm, notch 45°according to ISO 37/2 parallel and perpendicular orientation.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 1 and lessthan 10 dg/min preferably has an Izod impact strength L (23° C., kJ/m2)of at least 55, preferably at least 60.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 1 and lessthan 10 dg/min preferably has an Izod impact strength II (23° C., kJ/m2)of at least 5, preferably at least 6, more preferably at least 7, morepreferably at least 8.

High MFI

The heterophasic propylene copolymer may have a MFI of at least 10dg/min, preferably at most 90 dg/min, e.g. 20 to 50 dg/min, asdetermined by ISO 1133 at 230° C.; 2.16 kg.

The thermoplastic polymer composition according to the inventioncomprising this type of propylene copolymer is typically used in thinwall packing applications both for food and non-food segments. Thisincludes pails and containers and yellow fats/margarine tubs and dairycups. Materials have a good heat deflection temperature making itparticularly suitable for hot fill applications. The compositionaccording to the invention combine a high crystallization temperature,good flow behaviour in combination with an improved stiffness and goodimpact performance, also at low temperatures. Accordingly, the presentinvention relates to thin wall packing applications comprising thethermoplastic polymer composition according to the invention comprisingthis type of propylene copolymer.

Preferably, the heterophasic propylene copolymer having a MFI of atleast 10 d/gmin as determined by ISO 1133 at 230° C.; 2.16 kg comprisesfrom 60 to 80 wt %, more preferably 65 to 75 wt %, of a matrix phasecomprising a propylene homopolymer and/or a propylene copolymercomprising at least 90 wt % of propylene and up to 10 wt % of ethyleneand/or at least one C₄ to C₁₀ alpha-olefin, and from 20 to 40 wt % of,more preferably 25 to 35 wt %, of dispersed phase comprising anethylene-alpha-olefin elastomer comprising from 40 to 65 wt % ofethylene and from 35 to 60 wt % of at least one C₃ to C₁₀ alpha-olefin,preferably propylene. The thermoplastic polymer composition according tothe invention comprising this type of propylene copolymer with arelatively large amount of rubber shows a particularly desirableshrinkage property. Such polymer composition is especially suitable forthin wall packaging.

Preferably, the propylene homopolymer of the matrix phase has a MFI ofat least 50 dg/min, preferably at least 75 dg/min and preferably at most90 dg/min.

Preferably, the ethylene-alpha-olefin elastomer of the dispersed phasehas a MFI of 0.1 to 10 dg/min, e.g. 0.3 to 5 dg/min.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 10 dg/minpreferably has a MFI of at least 30 dg/min, e.g. 40 to 60 dg/min.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 10 dg/minpreferably has a flexural modulus L of at least 1400 MPa, morepreferably at least 1500 MPa.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 10 dg/minpreferably has a flexural modulus II of 1400 MPa, more preferably atleast 1500 MPa.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 10 dg/minpreferably has an Izod impact strength L (23° C., kJ/m2) of at least 5,preferably at least 6.

The thermoplastic polymer composition according to the invention whereinthe heterophasic propylene copolymer has a MFI of at least 10 dg/minpreferably has an Izod impact strength II (−20° C., kJ/m2) of at least5, preferably at least 6

The thermoplastic polymer according to the invention may contain otheradditives, of which suitable example include clarifiers, stabilizers,e.g. UV stabilizers, acid scavenger, release agents, plasticizers,anti-oxidants, lubricants, anti-statics, scratch resistance agents,recycling additives, coupling agents, anti-microbials, anti-foggingadditives, slip additives, anti-blocking additives, polymer processingaids, organic peroxides to control melt rheology, and the like. Suchadditives are well known in the art. The skilled person will know how toemploy these additives in conventional effective amounts.

The thermoplastic polymer composition according to the invention mayalso contain one or more of usual additives, like those mentioned above,including stabilisers, e.g. heat stabilisers, anti-oxidants, UVstabilizers; colorants, like pigments and dyes; clarifiers; surfacetension modifiers; lubricants; flame-retardants; mould-release agents;flow improving agents; plasticizers; anti-static agents; impactmodifiers; blowing agents;

fillers and reinforcing agents; and/or components that enhanceinterfacial bonding between polymer and filler, such as a maleatedpolypropylene, in case the thermoplastic polymer is a polypropylenecomposition. The skilled person can readily select any suitablecombination of additives and additive amounts without undueexperimentation. The amount of additives depends on their type andfunction; typically is of from 0 to about 30 wt %; preferably of from 0to about 20 wt %; more preferably of from 0 to about 10 wt % and mostpreferably of from 0 to about 5 wt % based on the total composition.

The thermoplastic polymer composition of the invention may be obtainedby mixing the nucleating composition according to present invention withthe thermoplastic polymer, and optionally other additives by using anysuitable means. Preferably, the thermoplastic polymer composition of theinvention is made in a form that allows easy processing into a shapedarticle in a subsequent step, like in pellet or granular form. Thecomposition can be a mixture of different particles or pellets; like ablend of a thermoplastic polymer and a masterbatch of nucleating agentcomposition, or a blend of pellets of a thermoplastic polymer comprisingone of the two nucleating agents and a particulate comprising the othernucleating agent, possibly pellets of a thermoplastic polymer comprisingsaid other nucleating agent. Preferably, the thermoplastic polymercomposition of the invention is in pellet or granular form as obtainedby mixing all components in an apparatus like an extruder; the advantagebeing a composition with homogeneous and well-defined concentrations ofthe nucleating agents (and other components).

The thermoplastic polymer composition may then be processed by anyconventional technique known in the art into a shaped article. Suitableexamples include injection moulding, injection blow moulding, injectionstretch blow moulding, rotational moulding, compression moulding,extrusion and extrusion compression moulding, extrusion blow moulding,sheet extrusion, film extrusion, cast film extrusion, foam extrusion,and thermoforming.

The invention therefore further relates to a shaped article comprisingthe thermoplastic polymer composition according to the invention. Inparticular, when the thermoplastic polymer of the thermoplasticcomposition according to the invention is a heterophasic propylenecopolymer having a MFI of at least 1 and less than 10 dg/min, suitablearticles include shells, crates, boxes, appliances automotive exteriorparts like bumpers, automotive interior parts like instrument panels andautomotive parts under the bonnet. When the thermoplastic polymer of thethermoplastic composition according to the invention is a heterophasicpropylene copolymer having a MFI of at least 10 dg/min, suitablearticles include thin wall packing applications both for food andnon-food segments, including pails and containers and yellowfats/margarine tubs and dairy cups.

Although the invention has been described in detail for purposes ofillustration, it is understood that such detail is solely for thatpurpose and variations can be made therein by those skilled in the artwithout departing from the spirit and scope of the invention as definedin the claims.

It is further noted that the invention relates to all possiblecombinations of features described herein, preferred in particular arethose combinations of features that are present in the claims.

It is further noted that the term ‘comprising’ does not exclude thepresence of other elements. However, it is also to be understood that adescription on a product comprising certain components also discloses aproduct consisting of these components. Similarly, it is also to beunderstood that a description on a process comprising certain steps alsodiscloses a process consisting of these steps.

The range of values “A to B” used herein is understood to mean “at leastA and at most B”.

The invention is now elucidated by way of the following examples,without however being limited thereto.

EXAMPLES Example 1

Several samples were prepared using a starting material having a meltflow index (MFI) of 1.5 dg/min. This material is a propyleneheterophasic copolymer having a propylene polymer matrix wherein thepropylene-based matrix (in this case a propylene homopolymer) is presentin an amount of 75.5 wt % based on the total heterophasic propylenecopolymer and 24.5 wt % of an ethylene-propylene copolymer consisting of56.5 wt % of ethylene.

The heterophasic propylene copolymer (4.1 kg) was extruded in a twinscrew ZE21 extruder with 2.5 wt % talcum (Imerys steamic OOSD/G finetalcum) and this material was shifted with 0.12 wt % (based on the totalcomposition) Luperco 802PP40 (di(tert-butylperoxyisopropylbenzene) asthe peroxide to the desired melt flow index for the finished material.The formulation of these materials contained in addition 500 ppm of theprocessing aid Calcium stearate, 2000 ppm of the stabilizer Irganox B225and 500 ppm HPN20E. The talcum, peroxide, calcium stearate, Irganox B225and nucleating agent were mixed with the heterophasic copolymer prior todosing it to the hopper of the extruder.

The temperature profile in the extruder was20-20-40-100-170-230-240-240-240° C., at a throughput of 2.5 kg/h at 300rpm.

For purpose of the present invention, stiffness is determined bymeasuring the flexural modulus according to ASTM D790-10. Flexuralmodulus was determined on 3.2 mm thick specimens according to ISO37/2,parallel and perpendicular orientation.

For purpose of the present invention, impact strength is determined bymeasuring the Izod impact strength at 23° C. according to ISO 180 4A,Test geometry: 65*12.7*3.2 mm, notch 45° according to ISO 37/2 paralleland perpendicular orientation.

For purpose of the present invention, flow is determined by measuringthe melt flow rate, also called melt flow index or melt index accordingto ISO1133 (2.16 kg/230° C.).

For purpose of the present invention, CLTE is measured according to ASTMD696 in parallel and perpendicular direction. Two types of temperaturechanges are employed for the measurements: a temperature change from 20°C. to 80° C. and a temperature change from −30° C. to 30° C.

For purpose of the present invention, shrinkage 3-D is measuredaccording to ISO 294-4. Two types of shrinkage are measured: shrinkageafter 24 hours at 23° C. and shrinkage after 24 hours at 23° C. followedby 1 hour at 90° C.

The results are summarized in Table 1. In the Tables:

RC is the rubber content (propylene-ethylene copolymer) in theheterophasic copolymer; RCC2 is the C2 (ethylene) content in the rubberpart of the polymer.

RC and RCC2 were measured with IR spectroscopy, which was calibratedusing NMR according to known procedures.

MFI heterophasic copolymer is the MFI of the starting heterophasiccopolymer consisting of the matrix and the rubber.

MFI final is the MFI of the final extruded composition of theheterophasic copolymer and additives such as talc, nucleatingcomposition and peroxide.

Properties in the parallel and perpendicular directions are indicatedwith “II” and “L”, respectively.

Comparative experiments and further experiments were performed andproperties were measured as summarized in Tables 1-6.

TABLE 1 Medium MFI composition CEx 1 CEx 2 CEx 3 Ex 1 CEx 4 CEx 5 Matrix(wt % based on 75.5 75.5 75.5 75.5 75.5 75.5 the heterophasic copolymer)RC (wt % based on 24.5 24.5 24.5 24.5 24.5 24.5 the heterophasiccopolymer) RCC2 (wt %) 56.5 56.5 56.5 56.5 56.5 56.5 MFI matrix (dg/min)4.7 4.7 4.7 4.7 4.7 4.7 MFI rubber (dg/min) 0.044 0.044 0.044 0.0440.044 0.044 MFI heterophasic 1.5 1.5 1.5 1.5 1.5 1.5 copolymer (dg/min)MFI final (dg/min) 14 14 14 14 14 14 Talc (wt %) 0 2.5 0 2.5 0 2.5 HPN20(wt %) 0 0 0.05 0.05 0 0 ADK NA27 (wt %) 0 0 0 0 0.1 0.1 Irganox B225(stabilizer) (wt %) 0.2 0.2 0.2 0.2 0.2 0.2 Acid scavenger Calcium 0.050.05 0.05 0.05 0.05 0.05 stearate (wt %) Peroxide (wt %) 0.12 0.12 0.120.12 0.12 0.12 Flexural Modulus L (MPa) 958 1137 1107 1202 1144 1207Flexural Modulus II (MPa) 963 1127 1107 1198 1196 1274 Izod Impact L(23° C.,. kJ/m²) 59.85 66.23 61.4 66.76 56.64 60.48 Izod Impact II (−20°C.,. kJ/m²) 6.79 7.87 7.99 8.11 7.25 6.97

Comparison of CEx 2, CEx 3 and Ex 1 shows that the combination of talcand HPN20 has a synergistic effect on the flexural modulus.

Comparison of CEx 1 and CEx 4 shows that ADK NA27 also increases theflexural modulus, but the izod impact L is decreased. Comparison of CEx1, Ex 1 and CEx 5 also shows that the combination of talc and HPN20results in increase of both flexural modulus and izod impact, whereasthe combination of talc and ADK NA27 results only in increase offlexural modulus. Furthermore, the difference in flexural modulus L andflexural modulus II is small by the use of HPN20. The difference inflexural modulus L and flexural modulus II is larger when ADK NA27 isused.

TABLE 2 Medium MFI composition Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Matrix (wt %based on 75.5 75.5 75.5 75.5 75.5 the heterophasic copolymer) RC (wt %based on 24.5 24.5 24.5 24.5 24.5 the heterophasic copolymer) RCC2 (wt%) 56.5 56.5 62 56.5 62 MFI matrix (dg/min) 4.7 4.7 4.3 4.7 4.3 MFIrubber (dg/min) 0.044 0.044 0.04 0.044 0.04 MFI heterophasic 1.5 1.5 1.41.5 1.4 copolymer (dg/min) MFI final (dg/min) 14 14 14 20 20 Talc (wt %)2.5 0.5 0.5 0.5 0.5 HPN20 (wt %) 0.05 0.025 0.025 0.025 0.025 ADK NA27 00 0 0 0 Irganox B225 (stabilizer) 0.2 0.2 0.2 0.2 0.2 (wt %) Acidscavenger Calcium 0.05 0.05 0.05 0.05 0.05 stearate (wt %) Peroxide (wt%) 0.12 0.12 0.12 0.18 0.18 Flexural Modulus L (MPa) 1202 1128 1257 11351264 Flexural Modulus II (MPa) 1198 1127 1242 1108 1254 Izod Impact L(23° C., kJ/m²) 66.76 62.78 11.23 59.69 10.47 Izod Impact II (−20° C.,kJ/m²) 8.11 7.62 5.9 7.3 5.8

Comparison of Ex 2 and Ex 3, and Ex 4 and Ex 5 shows that the ethylenecontent in the ethylene-propylene copolymer rubber has an extremelylarge impact on the izod impact strength.

TABLE 3 Medium MFI composition CEx 1 CEx 6 Ex 2 CEx 7 CEx 8 Ex 4 Matrix(wt % based on 75.5 75.5 75.5 75.5 75.5 75.5 the heterophasic copolymer)RC (wt % based on 24.5 24.5 24.5 24.5 24.5 24.5 the heterophasiccopolymer) RCC2 (wt %) 56.5 56.5 56.5 56.5 56.5 56.5 MFI matrix (dg/min)4.7 20 4.7 4.7 20 4.7 MFI rubber (dg/min) 0.044 0.2 0.044 0.044 0.20.044 MFI heterophasic 1.5 6.3 1.5 1.5 6.3 1.5 copolymer (dg/min) MFIfinal (dg/min) 14 14 14 20 20 20 Talc (wt %) 0 0 0.5 0 0 0.5 HPN20 (wt%) 0 0 0.025 0 0 0.025 ADK NA27 0 0 0 0 0 0 Irganox B225 (stabilizer)(wt %) 0.2 0.2 0.2 0.2 0.2 0.2 Acid scavenger Calcium 0.05 0.05 0.050.05 0.05 0.05 stearate (wt %) Peroxide (wt %) 0.12 0.06 0.12 0.18 0.080.18 Flexural Modulus L (MPa) 958 1127 1128 930 1134 1135 FlexuralModulus II (MPa) 963 1121 1127 919 1115 1108 Izod Impact L (23° C.kJ/m²) 59.85 13.11 62.78 59.85 13.6 59.69 Izod Impact II (−20° C.,kJ/m²) 6.79 6.19 7.62 6.79 6.63 7.3

Comparison of CEx 1 and CEx 6, and CEx 7 and CEx 8 shows that theincrease in the WI of the matrix leads to an increase in the flexuralmodulus and a large decrease in the izod impact strength.

Comparison of CEx 1 and Ex 2, and CEx 7 and Ex 4 shows that the additionof both talc and HPN20 increases flexural modulus while maintaining theizod impact strength.

TABLE 4 High MFI composition Composition Matrix (wt % based on 81.5 theheterophasic copolymer) RC (wt % based on 18.5 the heterophasiccopolymer) RCC2 (wt %) 53 MFI matrix (dg/min) 82 MFI rubber (dg/min) 0.6MFI heterophasic copolymer 33 (dg/min) MFI final (dg/min) 55 Talc (wt %)0.5 HPN20 (wt %) 0.025 Irganox B225 (stabilizer) 0.2 (wt %) Acidscavenger Calcium 0.05 stearate (wt %) Peroxide (wt %) 0.026 FlexuralModulus II (MPa) 1536 Izod Impact L (23° C., kJ/m²) 6.3

A thermoplastic composition was obtained having a good flexural modulusand a sufficient level of impact strength.

TABLE 5 Medium MFI composition CEx9 CEx10 CEx11 CEx12 Ex6 CEx13 Matrix(wt % based on 75.5 75.5 75.5 75.5 75.5 75.5 the heterophasic copolymer)RC (wt % based on 24.5 24.5 24.5 24.5 24.5 24.5 the heterophasiccopolymer) RCC2 (wt %) 56.5 56.5 56.5 56.5 56.5 56.5 MFI matrix (dg/min)4.7 4.7 4.7 4.7 4.7 4.7 MFI rubber (dg/min) 0.044 0.044 0.044 0.0440.044 0.044 MFI heterophasic copolymer 1.5 1.5 1.5 1.5 1.5 1.5 (dg/min)MFI final (dg/min) 15.5 13.3 14.3 13.6 12.5 14.7 Talc (wt %) 0 0.5 0 00.5 0.5 HPN20E (wt %) 0 0 0.025 0 0.025 0 HPN68L (wt %) 0 0 0 0.05 00.05 Irganox B225 (stabilizer) (wt %) 0.2 0.2 0.2 0.2 0.2 0.2 Acidscavenger Calcium 0.05 0.05 0.05 0.05 0.05 0.05 stearate (wt %) Peroxide(wt %) 0.12 0.12 0.12 0.12 0.12 0.12 Flexural Modulus L 1068 1112 11661126 1192 1173 (23° C., MPa) Flexural Modulus II 1066 1100 1182 11331187 1155 (23° C., MPa) Izod impact L 57.06 57.81 58.37 55.98 58.4353.64 (23° C., kJ/m2) Izod impact L 7.06 7.08 7.51 7.34 7.3 6.9 (−20°C., kJ/m2) CLTE 20° C.-80° C. L 152.5 147.4 142.1 155.4 140.8 154.5(μm/m · K) CLTE −30° C.-30° C. L 110.9 108.4 104.6 113.6 101.3 113.6(μm/m · K) CLTE 20° C.-80° C. II 154.1 144.6 138.1 150.2 134.4 149.3(μm/m · K) CLTE −30° C.-30° C. II 107.7 103.6 98.3 106.6 94.8 105.1(μm/m · K) Shrinkage after 24 hrs at 1.5053 1.4588 1.4757 1.5731 1.44511.5935 23° C. L (%) Shrinkage after 24 hrs at 1.7338 1.6550 1.67531.8436 1.6414 1.8254 23° C. + 1 hr at 90° C. L (%)

Comparison of CEx 10, 11 and Ex6 shows that the combination of talc andHPN20 has a synergistic effect on the flexural modulus, CLTE andshrinkage.

Comparison of Ex6 and CEx13 shows that the combination of talc and HPN20is superior than the combination of talc and HPN68 in terms of theflexural modulus, impact strength, CLTE and shrinkage. Furthermore, thecombination of talc and HPN20 results in similar flexural modulus L andII, in comparison with the combination of talc and HPN68 which resultsin a large difference between flexural modulus L and II. The largedifference between flexural modulus L and II causes a large internalstress which is unfavorable.

Comparison of CEx9, Ex6 and CEx13 also shows that the combination oftalc and HPN20 results in improvements on the flexural modulus as wellas CLTE and shrinkage, whereas the combination of talc and HPN 68results only in increase of the flexural modulus.

TABLE 6 High MFI composition CEx14 CEx15 CEx16 CEx17 Ex7 CEx18 Matrix(wt % based on 81.5 81.5 81.5 81.5 81.5 81.5 the heterophasic copolymer)RC (wt % based on 18.5 18.5 18.5 18.5 18.5 18.5 the heterophasiccopolymer) RCC2 (wt %) 53 53 53 53 53 53 MFI matrix (dg/min) 82 82 82 8282 82 MFI rubber (dg/min) 0.6 0.6 0.6 0.6 0.6 0.6 MFI heterophasic 33 3333 33 33 33 copolymer (dg/min) MFI final (dg/min) 53.4 56.0 47.0 55.748.7 48.8 Talc (wt %) 0 0.5 0 0 0.5 0.5 HPN20E (wt %) 0 0 0.025 0 0.0250 HPN68L (wt %) 0 0 0 0.05 0 0.05 Irganox B225 (stabilizer) 0.2 0.2 0.20.2 0.2 0.2 (wt % ) Acid scavenger Calcium 0.05 0.05 0.05 0.05 0.05 0.05stearate (wt %) Peroxide (wt %) 0.026 0.026 0.026 0.026 0.026 0.026Flexural Modulus L 1303 1424 1551 1515 1612 1566 (23° C., MPa) FlexuralModulus II 1320 1426 1566 1501 1589 1544 (23° C., MPa) Izod impact L(23° C., kJ/m2) 6.41 5.95 6.6 5.71 5.98 5.7 Izod impact L (−20° C.,kJ/m2) 3.41 3.56 4.08 3.55 3.59 3.7 CLTE 20° C.-80° C. L 148.6 135.6130.1 143.3 122.3 143.3 (μm/m · K) CLTE −30° C.-30° C. L 108.3 96.2 89.4105.1 89.5 104.8 (μm/m · K) CLTE 20° C.-80° C. II 146.2 136.8 125.0139.6 120.4 137.7 (μm/m · K) CLTE −30° C.-30° C. II 103.8 94.3 83.5 98.084.9 95.9 (μm/m · K) Average shrinkage after 1.4183 1.4071 1.4150 1.49171.3884 1.4915 24 hrs at 23° C. (%) Average shrinkage after 1.6150 1.57151.6333 1.8254 1.5426 1.8183 24 hrs at 23° C. + 1 hr at 90° C. (%)

Comparison of CEx15, CEx16 and Ex7 shows that the combination of talcand HPN20 has a synergistic effect on the flexural modulus, CLTE andshrinkage.

Comparison of Ex7 and CEx18 shows that the combination of talc and HPN20is superior than the combination of talc and HPN68 in terms of theflexural modulus, impact strength, CLTE and shrinkage.

Comparison of CEx14, Ex7 and CEx18 also shows that the combination oftalc and HPN20 results in large improvements on the flexural modulus aswell as CLTE and shrinkage, whereas the combination of talc and HPN 68does not result in a large improvement in CLTE and the shrinkage isworsened.

1. A nucleating composition comprising: (a) a first nucleating agent,which comprises a cyclic dicarboxylate salt compound; and (b) a secondnucleating agent, which comprises talc, wherein the cyclic dicarboxylatesalt compound has the formula (I):


2. A thermoplastic polymer composition, comprising thermoplasticpolymer, an organic peroxide, and the nucleating composition accordingto claim 1, wherein said thermoplastic polymer is a heterophasicpropylene copolymer comprising a matrix phase comprising propylene and adispersed phase comprising an ethylene-alpha-olefin elastomer, whereinthe heterophasic propylene copolymer has a melt flow index of atleast
 1. 3. The thermoplastic polymer composition according to claim 2,wherein the heterophasic propylene copolymer comprises from 60 to 92 wt% of the matrix phase and from 8 to 40 wt % of the dispersed phase,wherein the matrix phase comprises a propylene homopolymer and/or apropylene copolymer comprising at least 90 wt % of propylene and up to10 wt % of ethylene and/or at least one C₄ to C₁₀ alpha-olefin, andwherein the ethylene-alpha-olefin elastomer of the dispersed phasecomprises from 40 to 65 wt % of ethylene and from 35 to 60 wt % of atleast one C₃ to C₁₀ alpha-olefin.
 4. The thermoplastic polymercomposition according to claim 2, wherein the heterophasic propylenecopolymer has a melt flow index of less than 10 dg/min.
 5. Thethermoplastic polymer composition according to claim 4, wherein thematrix phase has a melt flow index of at least 1 dg/min.
 6. Thethermoplastic polymer composition according to claim 4, wherein theethylene-alpha-olefin elastomer comprises from 40 to 60 wt % of ethyleneand from 40 to 60 wt % of propylene.
 7. The thermoplastic polymercomposition according to claim 4, wherein the thermoplastic polymercomposition has a melt flow index of at least 5 and less than 30 dg/min.8. The thermoplastic polymer composition according to claim 4, whereinthe thermoplastic polymer composition has a flexural modulus L of atleast 1000 MPa.
 9. The thermoplastic polymer composition according toclaim 4, wherein the thermoplastic polymer composition has an Izodimpact strength L (23° C., kJ/m²) of at least
 55. 10. The thermoplasticpolymer composition according to claim 2, wherein the heterophasicpropylene copolymer has a melt flow index of at least 10 dg/min.
 11. Thethermoplastic polymer composition according to claim 10, wherein thematrix phase has a melt flow index of at least 50 dg/min.
 12. Thethermoplastic polymer composition according to claim 11, wherein thethermoplastic polymer composition has a melt flow index of at least 30dg/min.
 13. The thermoplastic polymer composition according to claim 10,wherein the thermoplastic polymer composition has a flexural modulus Lof at least 1400 MPa.
 14. The thermoplastic polymer compositionaccording to claim 10, wherein the thermoplastic polymer composition hasan Izod impact strength L (23° C., kJ/m²) of at least
 5. 15. A shapedarticle comprising the thermoplastic polymer composition according toclaim
 2. 16. The thermoplastic polymer composition according to claim 4,wherein the thermoplastic polymer composition has a melt flow index ofat least 5 and less than 30 dg/min, wherein the matrix phase has a meltflow index of at least 1 dg/min and less than 50 dg/min, wherein theethylene-alpha-olefin elastomer comprises from 40 to 60 wt % of ethyleneand from 40 to 60 wt % of propylene, wherein the thermoplastic polymercomposition has a flexural modulus L of at least 1000 MPa, and whereinthe thermoplastic polymer composition has an Izod impact strength L (23°C., kJ/m²) of at least
 55. 17. The thermoplastic polymer compositionaccording to claim 16, wherein the thermoplastic polymer composition hasa flexural modulus L of at least 1100 MPa, wherein the thermoplasticpolymer composition has an Izod impact strength L (23° C., kJ/m²) of atleast
 60. 18. A shaped article comprising the thermoplastic polymercomposition according to claim
 16. 19. The thermoplastic polymercomposition according to claim 2, wherein the heterophasic propylenecopolymer has a melt flow index of at least 10 dg/min, wherein thematrix phase has a melt flow index of at least 50 dg/min, wherein thethermoplastic polymer composition has a melt flow index of at least 30dg/min, wherein the thermoplastic polymer composition has a flexuralmodulus L of at least 1400 MPa, and wherein the thermoplastic polymercomposition has an Izod impact strength L (23° C., kJ/m²) of at least 5.20. The thermoplastic polymer composition according to claim 19, whereinthe thermoplastic polymer composition has a flexural modulus L of atleast 1400 MPa, and wherein the thermoplastic polymer composition has anIzod impact strength L (23° C., kJ/m²) of at least
 6. 21. A shapedarticle comprising the thermoplastic polymer composition according toclaim 19.